Question 74409: Dear sir.
My homework is quite hard for me so if you can help me i will be very grateful....
I have got to find the pairs e.g 4 times b = 4b but what is 2(x-1) and 4 times ( x-1)
Answer by bucky(2189)   (Show Source):
You can put this solution on YOUR website! 2(x - 1) and 4 times (x - 1)
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First, 2(x - 1)
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The lack of a math symbol (+,-,/,*) between the 2 and the parentheses is understood to
mean that this is understood to be multiplication. Then 2(x-1) means that you should multiply
2 times both of the terms inside the parentheses.
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So 2(x - 1) means to multiply 2 times x to get 2x and then multiply 2 times -1 to get -2.
The answer is that the pairs you are looking for are 2x - 1. This process is called
distributed or distributive multiplication.
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The same thing is done for your second problem 4 times (x - 1). Multiply the 4 times x to
get 4x and next multiply the 4 times -1 to get -4. So the answer to this problem is
4x - 4.
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Sometimes the problem may have even more terms in the parentheses. For example:
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8(a + b - c)
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Just multiply 8 times each of the terms in parentheses to get the answer as:
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8a + 8b - 8c
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Now let's try something a little different that might help you see what is happening.
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Suppose you were given the problem:
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3(1 + 2 + 4)
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You could work this problem several ways. You could work it by multiplying each of the terms
in the parentheses by 3 to get (3*1) + (3*2) + (3*4) and after each of these three
multiplications are done you get 3 + 6 + 12. When you add these up you get 21.
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Or another way to do the problem 3(1 + 2 + 4) would be first to add the numbers in the
parentheses and then multiply by 3. When you add 1 + 2 + 4 you get 7 and the problem is
then 3(1 + 2 + 4) = 3*(7) = 21. The same answer as before. So either way results in
the same answer.
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Hope this helps you understand how to do these multiplication problems.
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